Spring brake



B. F. SHIELDS ET AL SPRING BRAKE Filed Dec. 20. 1921 3Sheets-Sheet 1 26I6 VIIALIJI/II we NTORS Bea 221221 7. Shield: Czar/es 61 Clo/22h 'ealye)7; M'ndel/ BY ATTORNEY Sept. 2 1924.

B. F. SHIELDS ET AL S PRING BRAKE 3 Sheets-Sheet 2 Filed Dec. 20

lNVENTORS Ben 27121127 7'7 5/1/2/05' C'liar/fis 61 Craml Glee/ye Mizdel/BY ATTORNEY v Sept. 2. 1924. 1,507,034

. B. F. SHIELDS ET AL SPRING BRAKE Filed Dec. 20, 1921 3 Sheets-Sheet 5INVENTORS flea/(1min 7T fife/d: Charles E. Cromie George 17. Mkde/l.

BY ATTORNEY Maw Patented Sept. 2, 1924.

UNITED STATES BENJAMIN IF. SHIELDS, CHARLES G. CROMBIE, AND GEORGE- A.WINDELL, OF SEATTLE,

1, 4 PATENT OFFICEQi WASHINGTON.

spams BRAKE. 1 f 1 Application filed December 20, 1921. Serial No.523,701;

To all whom it may concern: 7

Be it known that we, BENJAMIN 'F. SHIELDS, CHARLES G. CRoMBIn, andGEORGE A. VINDELL, citizens of the United States, residing at Seattle,in the county of King and State of Washington, have invented certain newand useful Improvements in Spring Brakes, of which the following is ashock absorblng devices known as the snubspecification.

This invention relates to improvements in spring brakes or devices forabsorbing excess deflection and rebound of the springs of motor vehiclesand is an improvement on the spring brake or shock absorber disclosed inthe application of Benjamin F. Shields, Serial Number 435,093, filedJan. 5, 1921. The object of this improvement is to provide a springbrake of this nature that will have, in its operation, a neutral zone inwhich it will not exert any retarding ef-' feet on the spring with whichit is con-- nected but will leave the spring absolutely free to operatein the usual manner, the neutral or ineffective zone of the spring brakecorresponding to the movement or flexure of the spring under normaloperation and the spring brake being arranged to exert a retarding orbrake effect in response to excess deflection or an excess upward throwof the spring.

' Vehicle springs of the type used on automobiles are ordinarilyconstructed so that when they are subjected to a normal load and areworking under normal conditions they will operate more smoothly and withgreater efliciency if they are left entirely free than they will ifthey, are hampered and their free and easy movement is interfered withby attachments of the usual form known as shock absorbers, 'snubbers andthe like.

All of the shock absorbers, snubbers and like devices with which we arefamiliar at the present time operate in such a manner as to hamper thefree and easy movement of the vehicle springs when they are workingunder normal load and normal conditions. Some of these devices tend toexert a retarding action as soon as any movement or deflection of thevehicle spring from its normal loaded position begins and continue toretard the deflection of the spring with increasing force as itsdeflection increases, thereby having the eflect of adding to thestiffness of thespring and causing the ve hicle body to ride less easilyand less smoothly. This type of device usually is arranged to absorbrecoil'or rebound of the vehicle,

body after adeflection of the spring; thus making the springs work muchmore slowly even under ordinary normal defiect1onsthan they otherwisewould. Another class 0 f her type permit the spring to deflect-freel butcatch it at the point of greatest deflection and exert a retardingeffect throughout the entire recoil movement of the spring thus failingto reinforce the spring when it.

' This invention overcomes the objections above pointed out by providinga spring brake that will operate freely and without retarding the actionvof the vehicle spring as long as such vehicle spring is working undernormal load and normal conditions,

and is only subjected to normaldeflection and rebounding movements butthat will be gin to exert a retarding"- or brake effect on the spring assoon as the movements of de flection or the rebounding movements are inexcess of a predeterminednormal; such spring brake being arrangedtoretard the rebound or upward throw of the spring after an excesslvedeflection but to release" as soonas the spring comes again within. the

limits of its normal movement or withinthe neutral zone and to againtake hold to check excess rebound or upward throw of the. ve-

hicle body if the rebound continu'es entirely through the neutral zoneand exceeds thei predetermined limit of normalmovement.

The ordinary vehicle spring is constructed to support a certain known.load and to vibrate treely. easily and smoothly between .certain limits.the space between such limits being-herein" termed. the neutral zone ofoperation of the spring. Whenthe spring is deflected beyond the limit ofthe neutral zone it will ordinarily rebound with excessive force, thusrendering the vehicle vun- I pleasant and dangerous to ride 1n andsomein the neutral zone but acts as an instantaneous and positive brakeon such spring it the deflection or the rebound of the spring are ceedsthe limits of the neutral zone.

By operating in the manner above described this spring brake serves toreinforce and stiiten' the vehicle spring only in case of an unusuallysevere shock and to I'llDSOl'b rebound only when such rebound in excessof the normal.

This spring brake is readily adjustable so that it may be set to takehold and release at any point in the movement of the spring. therebymaking the spring brake readily adaptable to springs and vehicles oi(litterent size weight and strength.

This spring brake is simple and strong in construction, reliable andefficient in operation, neat in appearance, not expensive to manufactureand easy to install on vehicles having springs of the ordinary type ofconstruction.

Other, advantages in the form of construction and arrangement of partsof the device will be apparent fromthe following description taken inconnection with the accompanying drawings.

In the accompanying drawings Figure 1 is a view in side elevationshowing this spring brake as it may appear when installed.

Fig. 2 is a detached view in elevation of the spring brake, certainoperative positions that parts of the same may assume being shown bybroken lines.

Fig. 3, is a view in cross section substantially on broken line 8, 3 ofFig. 2.

Fig. 4 is a detached view in perspective of a detail of the invention.

Fig. 5 is a sectional view showing bracket means for securing thehousing of the spring brake to the inside of a "frame channel.

Fig. 6 is a sectional view substantially on a broken line 6, 6 of Fig.3. I

Fig. 7 is a sectional view of internal brake members or shoesshowingcertain parts in elevation.

Fig. ,8 is a detached plan view of a detail of the invention.

Fig. 9 is a fragmentary view of a modified form of a detail of theinvention.

Fig. 10 is a sectional. view of a modified form of spring brake.

Fig. 11 is a view in elevation on a reduced scale showing the exteriorof the device shown in Fig. 10.

Figs. 12, 13, 14 and 15 are sectional views showing four differentmodifications of the invention.

Referring to the drawings. throughout which like reference numeralsdesignate like.

ing substantially flush with the rear side of the housing 16 if thehousing is to be secured to the outer side of the channel 18 and beingoffset to the rear of? such housing as shown in Fig. 5 if the housing isto be secured'to the inner side of the channel 18.

It will be understood that the spring brake may be connected in manydifferent ways with motor vehicle springs and frames. or with relativelyvibratory parts of mechanical devices, Fig. 1 only showing one typicalinstz-illation of the same.

The interior ot the housing 16 is provided with a centrally arrangedintegrally formed c -ilindrical bearing member or hub 10 on which thetubular portion 20 of a brake shoe supporting bracket is rotatablymounted.

The tubular bracket portion 20 is pro vided at the outer end with anoutwardly directed annular flange 21 that is arranged to fit within acircular groove or rabbet 22 in the edge of the drnmlb ant. at the innerend with two diametrically opposite lugs and 25!: that are each providedwith a pcritoratioi that is disposed in alignment with a corre spondingperforation in the flange 21.

The brake shoe supporting bracket is retained within the housing 16 byadisk 26 that fits within an annular groove or rabbe; in the innercircumferential portion of the flange 21 and is rigidly secured to thetubular hub portion 19 of the housing by screws 2?, thereby leaving thebrake shoe supporting bracket tree to turn within the hous ing 16.

The annular flange 21. of the brake shoc supporting bracket is providedwith an intcgral or otherwise rigidly connected lever arm 28 thatterminates in a ball 29 and is arranged to be connected as by a link 3and clamp bracket 31 with an axle 32 unon which rests, a spring 33 thatsupports the Frame member 18, the arrangement beingsuch as to causeoscillation of the brake shoe sup-- porting bracket in response torelative movement between the frame member 18 and the axle 32.

Disposed within the housing or drum 16 between the end tlangc 21 and thelugs and 24: are two scmi-circular brake shoes 51% threaded through theflange 21 and is provided with a lock nut 39 so that the position of thebrake shoes may be adjusted with respect to the interior surface of thedrum 16 with which they are arranged to engage by V )roiecting thetapered pin further into or withdrawing it from between the inclinedends of the adjacent brake shoes.

The brake shoes are covered with the usual v brake lining 40 having ahigh coelhcient of friction and the cam 36 is flattened on oppositesidesas shown so that when itis turned the brake shoes will be expanded andthe linings lll caused to trictionally engage with the inner surface ofthe drum 16. The brake shoesarc ordinarily adjusted by mov ing thetapered pin 38 so that they rest very lightly against or just clear ofthe walls of the drum 16 andwill'permit a certain amount of turning" o'tthe cam 36 in either direction before they begin to bind pen the wallso't' saiddrum and exert a retarding'action, thus leaving the vehiclespring on which they are installed free and unhampereiil under ordinaryoperation but being ready to exerttheir braketorce to prevent anexcessive deflection oifrebound of the vehicle spring".

The interior Iivallot the drum 16 isms in ly shaped opening in a leverarm 14.- by

which the cam may he turned The lei 'erarm has a slot 42:") extendinglengthwise thereof that is slida'ble on a screw 4-6 which is screwerlinto a'ndis rigid with the disk 26 at a point removed :from the centerthereoi so that when the operatinclever 28 is oscillated thc leverarinll will be turned. atia different angle and will thereby turn thecam 36 and expand the disposed at different distances tromthe center forthe reception of the screw 46 to atlord ad ustments tor turning thelever arm letthrourgh ditlf'erent angles in response to a predeterminedthelever arm 2i will vary directly as the distance of the screw lti'trom the center of the disk 26/ in Fig; 9 we have shown the ends of thebrake shoes 34 as orovided with bearin p I, v V zr plugs 4-8 or hardenedmetal, the peripheral YOi'bIOUS of which protrude sl ghtly from theflattened end surfaces of the braheshoes and are arranged to fit withingrooves l9 in the sides of a. cam that corresponds in purposeandd'unction to the cam '36 and that serves to move the endso't' the twobrake shoes apart when itis turned.

fined members while the brake shoes and the bracket that carries suchbrake shoes are movable within the housing, the brake 111T- as' shown inFigs. r I v angular movement of of the operating lever 28 will turn thelever The turning movement imparted tothe cam 36 relative to the anvings tflbeing arranged to frictionally engage with "the internalsurface of the housing drum 16. i

The brake shoes are adjusted by move-- ment of the tapered pin 38 sothat when the vehicle is at rest under an average load the I 1-0 may beCompensated for by adjustment of the tapered pin 38.

The flattened surfaces, of the brake shoes against which the cam 36operates will preferably be' formed of hardened pieces of 7. steel orsimilar inaterial that arewelded o votherwise rigidly secured to the.ends oi the brake shoes 34: as shown 1n Fig. 6.

v The space betweenthe points at which the brake is firmly applied bymovement of the operating lever 28, in opposite direction:- from theposition of rest under normal load is thei space herein termed the"neutral zone and such space may be'varied by adpistmg theposition of thescrew 46 in the holes 1'? it being apparent that if such screw which.forms a stationary fulcrum for the lever arm'ett is moved further'awayfrom the center or axisabout which the bracket that carries the cam 36rotates 1t w llcauses greater amount of turning movement to be impartedto thecam in pro-portion to a Y "given turning movement of the operatingbrake shoes. I The disk- 26 has several holes levert'For instancefit'the screw 46 is positioned so that It will be between the center of thedrum 16 and the cam 36 when; all parts are in their normal position ofrest 1 and 2 any movement arm 445through a certain angle difiering' fromthe angle through which the operating;

through a greater angle in response to the Thus it will bennderstoodthat it the "screw 46 is moved from the position shown in r 2 toward thecam 36 the scope of the neutral The housing 16 and disk 26 arerelatively zone will be decreased andif suohscrew 4:6 is moved'to agreater distance from the cam 36 the scope of the neutral Z0118 will beincreaseda l n ha The cam 36 of the form shown in Fig. 6 and the cam ofthe form shown in Fig. 9 are both substantially true circles on theirrounded or noncontacting sides so that a relatively slight turningmovement of the cam will expand the brake shoes to a maximum and suchbrake shoes will remain fully expanded but will not be set tighter inresponse to further turning movement of the cam. As the cams areturnedback from an extreme position toward the normal position they willhold the brake shoes fully expanded until they reach the limit of theneu tral zone and will then release quickly but not instantaneously, theobject of the particular shape of the cams being to cause the brakeshoes to take hold and release as quickly as possible at the limits ofthe neutral zone without producing a shock or strain andto establish amaximum expan sion beyond which the brake shoes can not be moved byfurther turning of the lever, thereby making it impossible to set thebrakes tightly enough to lock the device and prevent it from coming backto thenormal position.

In the normal position of rest the operating lever 28 will besubstantially at right angles to the link 30 and the effective lever armthrough which the vehicle spring is acting to move the brake will be atits maxi mum but as the operating lever 28 is moved above or below thenormal position of rest the effective lever arm through which the 1force of the spring is being exerted against the brake will gradually belessened, thus causing the effective retarding force of the brake toincrease gradually in response to further movement of the operatinglever after the brakes are set to the maximum by the full expansion ofthe brake shoes and to decrease gradually as the operating lever movesfrom an extreme angular position back toward the neutral zone. will beseen that this device offers the greatest resistance at the point ofmaximum deflection of the spring or of maximum rebound of the partsconnected with such spring. I

From the above description it will be seen that this spring brake willnot interfere with the free and easy movement of the vehicle springwhile the vibrations of such spring are within the limits of the neutralzone but thatthe spring brake will exert a retarding effect on anymovements of the spring that are outside the limits of the neutral zone.

In Figs. 10 and 1.1 we have shown a modification of the invention inwhich semi-circular brake shoes or bands 51 are adjustably secured as byblocks 52 and screw 53 to a fixed housing 54 and are arranged to becontracted on a movable drum 55 which is secured to a cover plate 56that has a rig- Thus it the manner shown by shackles 58 that are fprovided with a rigid stud 59 which projects outwardly through an endplate 60 on the housing 54 and terminates in a flattened end 61 that isconnected with a lever arm 62, having a longitudinally extending slot 63that fits slidably over a rigid screw stud 64 in the cover plate 56.When the cover plate is turned the lever arm 62 will be moved into anangular position thereby turning the shackle links and contracting thebrake bands 51 on the drum 55. Slight clearance is provided between thebrake bands 51 and drum 55 so that the brake bands will not be appliedto the drum until after the actuating arm 57 has been moved through apredetermined angle, thus providing a neutral Zone in the operation ofthe device.

In Fig. 12 we have shown a modification of the invention in which afixed housing or drum 65 having a fixed centrally located cam member 66is arranged to be engaged by a movable brake shoe 67 having adjacentrolls 68 at its ends that are adapted to be movedapart by a wedge 69 onan arm 70 that passes through a guide 71 and has a roller 72 on itsinner end that rolls on the surface of the cam 66. The brake shoe 67 maybe anchored to the moving parts by a pin or stud 7 3 arrangeddiametrically opposite to the wedge 69.

Fig. 13 shows a modification of the invention comprising a fixed housing74 having a semi-circular brake q segment 75 rigidly secured thereto inspaced relation from the walls thereof, said segment preferably beingprovided with a roughened exterior surface that is arranged to beengaged by the roughened interior surface of a movable brake segment 76that is arranged to wedge between the segment 75 and the walls of thebrake" drum. The segment 76 may be moved by a lever arm 77, post 78 andoperating lever 7 9 that are all rigidly connected with each other, thepost 78 being mounted for,rotation in the ends of the housing 74. Aliinited. amount of movement from the position of rest is permittedbefore the movable segment 76 engages the fixed segment 75, thusproviding a neutral zone in the operation of the device.

Fig. 14 shows a modified form of the invention in which a housing ordrum 80 and a central cam 81 are relatively fixed or stationary and abrake shoe 82, flat springs 83, operating rods 84 and rollers 85 aremovable within the housing 80 and around the cam 81 by means of anoperating lever '86. A very slight clearance between the brake shoe 82and drum80 when the roll-- ers are-at the lowermost points on the cam,

as shown. insures a neutral zone in the op eration of the device. As themovable parts are turned the rollers 85 by engaging with the cam 8i,expand the brake shoe 82 against the drum, thereby producing a retardingefi'ect. r

Fig. 15 shows-a modification oi -the 'in vention. in whiclra housing ordrum ST, springs, 88 and operating rods 89 having rollers 90 on theinner ends thereof are relatively'lixed and a cam 91 and brake shoe 92are movable relative to the fixed parts by an operating lever 93. Theoperating lever in this-form of construction may be partly within thehousing 87 and may project outwardly through a suitable opening in suchhousing, not 'shown- When the operating leven is moved the cam 91 willmore the'operating rods 89 outward ly, thus expanding the brake shoe 92against the wall of the drum 8?. A very slightclearance betweenthel'brake shoe 92 and drum 87 insures a neutral zone in the operationof the device. i

The foregoing description, together with the accompanying drawing,clearly illus irates the form of construction and method of operation"of this invention, but it will be understoodthat this disclosureis'mereiy illustrative and that such changes 'in form, dimensions andarrangement of parts may be resorted to as are within the scope of thefollowing claims:

VVh-at we claim is:

l. A spring brake tor connection to the frame and axle of a springsupported vehi-v cle, embodying brake means, having a constant neutralzone of operation correspond ing to a predetermined normal vibratormovement between said frame and axle and in which it offers noresistance to said vibratory movement, said brake means being arrangedto offer resistance to movement in either direction outside of saidconstant neutral zone.

2. A spring brake for connection to the frame and axle of a springsupported vehicle, embodying brake means having a neutral zone in whichit otters no resistance to movement for a predetermined distance ineither direction from a normal inoperative position, said neutral zonebeing constant with respect to said normal inoperative position, saidbrake means being arranged to offer resistance to movement in alldirections outside of said neutral zone, said resistance increasing inresponse to movement away from said neutral zone and decreasing inresponse to movement toward said neutral zone. 1 I

3. A spring brake for connection to the frame and axle of a springsupported vehicle, embodying brake means, having a constant neutral zoneof operation correspond.-

ing to a predetermined normal vibratory movement between saldframe andaxle and.

in which itoffers no resistance to said Vibratory movement, said brakemeans being arranged to offerresist-ance to movement in either directionoutside of said constant neutral zone, and means for adjusting saidspring brake to vary the amplitude of said neutral zone. I v v r 4:.A'spring brake for connectionlto the two relatively vibratory portionsof a spring supported vehicle, embodying a-brake housing arranged to besecuredto one of said portions, an operating lever having one endpivotally connected with said housing, a link connecting the other endof said operating lever with said other vibratory portion,'brake-meansdisposed in saidhousing and connected with said f operating lever, saidoperating lever having a normal inoperative position when said twovibratory portions are at rest and having a neutral zone constant. withrespect to saidinoperativeposition, in which said brake means of fers noresistance to movement for a predetermined distance in either directionfrom said inoperative position, said brake means being arranged to offerresistance to movemerits in all directions outside of said neutral zone.

A spring brake for connection to the frame and axle of a springsupported vehicle, embodying a cylindrical brake housing arranged to besecured to said'frame, said housing including a brake drum, a brake shoesupporting bracket rotatably disposed within said housing,brake shoesdisposed within said housing and movable with said bracket, an operatinglever connectedwith said bracket, link means connecting said op-'.erating lever with said vehicle axle for moving said operating lever,and means gov v erned by the movement of said operating lever forexpanding said brake shoes against said brake drum. I

6. A spring brake for connection to the frame and axle of a springsupported vehicle, embodying a cylindrical brake housing arranged t besecured to said frame said housing having an tinteriorly disposed brakedrum, a brake shoe supporting bracket rotatably disposed within saidhousing, brake shoes disposed within said housing and movable with saidbracket, an operating lever connected with said bracket, link meansconnecting said operating lever with the vehicle axle, a cam connectedwith said brake shoes and arranged to expand said brakeshoes. andadjustablemeans for actuating said cam in response to movement of saidoperating lever.

7. A spring brake of the class described embodying a brakedrum, a brakeshoe supporting bracket rotatably disposed Withm said drum, semicircularbrake shoes disposed within said drum and movable with said bracket anoperating lever connected with said bracket for turning the same, a camrotatably mounted between adjacent ends of said brake shoes and arrangedto be turned to expand said brake shoes quickly and then hold the samein a relatively fixed expanded position, a lever arm fixedly secured tosaid cam, and "fulcrum means for said lever arm adjustable into variousfixed positions with respect to said cam whereby the angular movement ofthe cam relative to the movement of the brake shoe supporting bracketmay be varied.

8. A spring brake for connection to the frame and axle of a springsupported vehicle, embodying a cylindrical brake housing arranged to besecured to said vehicle frame and having an internal brake drum,semicircular brake shoes arranged to frictionally engage with said drum,an internal hub concentric with said housing, a brake shoe supportingbracket mounted for rotation Within said housing and arranged to carryaid brake shoes, relatively inclined surfaces on said brake shoes at oneside of said brake drum, a tapered pin adjustable between said inclinedsurfaces, parallel end surfaces on said brake shoes at the other side ofsaid brake drum, a cam rotatably interposed between said parallel endsurfaces, an operating lever for turning said brake shoe supportingbracket, link means for connecting said operating lever to the vehicleaxle, and means for turning said cam when said operating lever is moved.

9.A spring brake for connection to the frame and axle of a springsupported vehicle, embodying a cylindrical brake housing arranged to besecured to said vehicle frame and having an internal brake drum,semicircular brake shoes arranged to frictionally engage with said drum,two adja cent ends of said brake shoes being parallel to each other andthe other two adjacent ends being, inclined with respect to each other,an integral hub concentric Within said housing, a brake shoe supportingbrack a point removed from the center thereof for guiding said lever armwhereby said cam Will be turned by movement of said operat ing lever.

Seattle, Wn. Dec. 8, 1921.

BENJAMIN F. SHIELDS. CHARLES G. CROMBIE. GEORGE A. VVINDELL.

